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I thought you were being humorous yesterday! Yes, that's precisely how it will help determine key. I thought we covered that back with the Moonlight - it must have slipped through with the furore of cross posting.

If you take a major scale and build a triad on any of it's seven degrees using two successive thirds you will form the seven primary chords of the key.

Note that western harmony is all built on thirds (alternate notes).

Because of the major scale pattern T T S T T T S you will always have a major chord on degrees 1, 4 and 5, forming the I, IV, and V chords.

On the second, third and sixth degrees you will always have minor chords, II, III, and VI.

On the seventh step you will always have a diminished chord forming the very tritone that is used in the dominant seventh chord from the fifth step.

Adding another third to each triad will form the secondary sevenths using notes 1,3,5 and 7 from each degree. On degrees 1 and 4 you will always have a major seventh (major third, minor third, major third). On degrees 2, 3 and 6 you will always get a minor seventh (minor third, major third, minor third).

On the fifth degree, the dominant, you will get a unique seventh (major third, minor third, minor third) which we call a dominant seventh (after the degree).

On the seventh degree you will get a half-diminished chord (minor third, minor third, major third).

Note that a minor is the relative minor of C major, D minor is the relative minor of F major and E minor is the relative minor of G major.

Now rewrite these chords in this order:

F major, C major, G majorD minor, A minor, E minor

Now compare that with a diagram of the circle of fifths.

Write the B diminished above the G major and add them together to form the dominant seventh. That's how Gary gets the rootless dominant 7b9 from a diminished seventh or a rootless dominant seventh from a simple diminshed triad.

That is lovely! I'd never noticed that before. It's a quarter of the circle of fifths, with major keys on the outside (or top, typed here) and relative minor keys on the inside (or bottom, typed here). These are also all the "nearby" keys for changing key one accidental at a time from the original key.

Rewriting with roman numerals, which helps me see the general pattern:

Code:

IV, I, V
IIm, VIm, IIIm

So it shows that each of the primary chords of a key, except for VIIdim, can become the I or Im chord of a nearby key.

Does this show substitutes also? So IIm can substitute for IV, VIm can substitute for I, and IIIm can substitute for V? Also VIIdim can substitute for V?

Write the B diminished above the G major and add them together to form the dominant seventh. That's how Gary gets the rootless dominant 7b9 from a diminished seventh or a rootless dominant seventh from a simple diminshed triad.

All clear on the circle of 5ths, but not clear on what you mean by adding Bdim to G major to form the dominant 7th.

On the 7th degree we have a diminished. When we add the 3rd above (will always be major third above) we have a half diminished.

The third above the diminished chord on the seventh degree will always be a major third above when in a major key.

The chord can either be called "half-diminished" or "minor 7 flat 5". There are two possible notations. One notation uses a circle with a slash that ought to be a superscript, but sort of like this (except make the circle smaller and higher): Bø. The other uses m7b5, like this: Bm7b5.

The pattern, major third, minor third, minor third is unique to the dominant/5th degree so we call it a dominant seventh (or just a plain seventh as opposed to a major seventh or minor seventh).

I am glad that you wrote both parts. There is a major trap in the theory books which I almost fell into myself. The form itself is as you wrote:G(major third)B(minor third)D(minor third)Fin root position.Or you can also see it as a major triad, where the "seventh" (F) is a minor 7 above the root G. In jazz or popular music where letter names for chords are used, it is commonly known as the "seventh chord". I prefer this in most cases, for a reason.

Dominant is one of the names of the degrees of a scale. These degrees are as follows: In a C major scale:C - Tonic (the tone that is set; i.e. it's in C major)D - Supertonic (means above the tonic)E - Mediant (a third above)F - Subdominant (it's under the dominant)G - Dominant (It plays a major or dominant role. It is the second strongest note that the music wants to go to.)A - Submediant (a third below)B - Leading note (has a strong pull that "leads" to the Tonic. That's why in a G7 chord, the B tends to rise to C).

These are "functions" or roles which in simpler music tend to happen, or that we often see happening in music. It goes together with our I, IV, V Roman Numerals which point to functions.

Dominant seven refers to the "dominant" or V chord specifically which has the seven, and it usually leads to the tonic in our V7 progression. It uses all of the notes in the key for major keys. In minor keys, the third is raised (In C minor, the Bb is raised to Bnat so we still have G7 and not Gm7, to get V7-I = G7-Cm). The Dom7 happens to have the shape of *(major third)*B(minor third)*(minor third)* that Richard has mentioned.

In music we will often see a "seven chord" with that shape where it is not playing the role of "dominant" leading to the tonic. That is why that name presents a problem unless we've sorted that out. When I discovered this, I went back and checked in my theory books. They make sure to only show examples of seven chords functioning as dominants, going to I, so students never ask awkward questions. I was almost trapped into thinking that seven chords can only be dominants (V's), because that's all the theory books presented.

In music we will often see a "seven chord" with that shape where it is not playing the role of "dominant" leading to the tonic. That is why that name presents a problem unless we've sorted that out.

No worries here. I have been playing 7th's forever and only since joining the analysis threads in the last month or so, have paid much attention to what a dominant really was/meant.

This is all really good information. I'm printing out some notes from this recent thread activity as I think will help immensely in my understanding and better analysis moving forward. There is actually a lot to absorb here, when working through all the keys, and minor keys everyone

I had learned to use the term "dominant seventh" if I need to be precise, regardless of whether it's functioning as V7 to I. This is so that the type of seventh chord which is "major triad plus minor seventh" has a name, just like all the other types of seventh chords:

Is there anything incorrect with this? You may notice I did not include minor triad plus major 3rd. I do not think I have ever come across this. But, suppose it would be a minor major 7, although I would have probably called it something entirely different.

You have the intervals and names correct. I think it's useful to know the intervals from the root as well.

For example, dropping back to triads: a major triad can be thought of as a major third followed by a minor third. It can also be thought of as a major third and a perfect fifth above the root. It's the latter description which leads to us talking about "the fifth of a chord.". For example, "C7 without the fifth" is C E Bb, and you might want to describe that voicing.

Similarly for sevenths above the root.

I also find it easier to calculate a seventh -- 1-3 half-steps below the tonic (an octave up) than I find it to calculate a major or minor third above the fifth.

I should say, I do like working through the stacked thirds descriptions, because I like running through all the possibilities for two or three stacked thirds. And, hey, now that I know about extended chords, why stop at just stacking three thirds in four note chords. On to four thirds in five note chords! Etc.!

Oh my! I haven't seen binary since taking a machine language programming course way back when, in which I barely got a pass. I see what you're doing. You're seeing patterns of majors and minors, rather than literally binary, yet you're also counting them off in binary. That's actually quite cool.

It does require accepting that a dominant seventh chord may be built (using accidentals) on a note which is not the dominant of the key you're in.

The fault is with the system. When it is built on the fifth degree of the scale it is the dominant seventh of the key. (In the ABRSM Manual of scales and arpeggios GBDF is called the dominant seventh of C not G7).

When it is formed on the tonic or fourth of the key it is a dominant seventh (type) chord.

In letter chord symbols the seventh is minor by default. In RN's the seventh is diatonic by default so C7 in key F is V7 but in C key is Ib7.________________

Clever work with the binary. A 'mirrored' system might be better; least significant bit on the right being the first third etc. then there's no awkward change in notation from fifths to sevenths.

If you extended this concept into the next octave you will reach a point where a stack of minor thirds has reached a higher interval than a stack of major thirds. Although the chords are tertian (built on thirds) they are actually alternate notes.

So is it conceptually a root, plus a third, plus another third, etc. or is it a root, plus a third (major or minor), plus a fifth (diminished, perfect or augmented), plus a seventh (major, minor, or diminished), etc.? And does it make a difference in practise? It might get rid of sixths, sus2's, and sus4's (but I have a theory about those anyway).

Originally Posted By: PianoStudent88

I don't claim this is any use for sonata analysis...

It helps to show the details in the fundamentals of chord construction/naming and the relation to the underlying scale. If it helps to make it clearer for you then it may help to make it clearer for others.

We're analysing sonatas as much to try and learn the musical language as the converse. Your thinking helps.

It helps to show the details in the fundamentals of chord construction/naming and the relation to the underlying scale. If it helps to make it clearer for you then it may help to make it clearer for others.

We're analysing sonatas as much to try and learn the musical language as the converse. Your thinking helps.

Agree. Certainly helps me.

So now, testing out my new found wisdom for M21-M27

I will name the chords here, as I believe this may pose a stumbling point for identifying key if I get these wrong.

The C#dim7 comes from the key of D minor, and is making the following Dm chord seem more inevitable. It is VIIdim7 in the key of D minor, and can also be seen as a rootless A7b9, a.k.a. V7b9 in the key of D minor.

Not saying we're in D minor at any point, just pointing out a use of accidentals to make a progression to a particular chord (in this case Dm) seem more inevitable.

I want to say that D is being briefly tonicized here, and C#dim7 comes from the land of secondary dominants, but I don't know if I'm using that language wrong. Greener, I don't know if we've talked about tonicization and secondary dominants in our analysis threads yet. I'll try to explain what I mean better, if someone else doesn't jump in first with a better explanation. Right now I'm trying to think about how to talk about the promised more basic information of chords in minor keys...

Before talking about chords in minor keys, I want to talk about roman numerals some more. I'm not sure I need this; I could just avoid roman numerals in what I'm going to say next. But I like roman numerals, because they show me patterns, so I want to be able to use them. So I have to talk about how I will use them in minor keys.

There are a couple of different ways of using roman numerals in minor keys. The way I'm going to show is not actually how I originally learned these; it's a system I learned later, but I think it's more flexible for the variety of harmonies one might want to analzye. The original system I learned worked best only for highly tonal music with a restricted set of chords and key changes.

In this post I'm going to just talk about roman numeral names for chords with accidentals. The post comes out quite long, and I'm not sure this is the best order to approach this in. So if this just makes your eyes glaze over, skip over it, and the next post will show more examples. It might be easier to pick this up just from examples rather than me trying to give this theoretical explanation first.

That said, here's the theoretical explanation. There's no music in this post; it's purely notation.

Roman numerals for chords with accidentals in a major key

Let's suppose that we're in a major key. Say, C major. Then we've seen, for example, the triads that are native to C major:

C, Dm, Em, F, G, Am, Bdim.

In roman numerals:

I, IIm, IIIm, IV, V, VIm, VIIdim.

Suppose I start to allow accidentals, while staying in the key of C major? What would I call, for example:

Fm (F Ab C)? Answer: IVm.

Em(maj7) (E G B D#)? Answer: IIIm(maj7).

D6 (D F# G A)? Answer: II6.

And so on. I just replace the letter with the appropriate roman numeral.

Roman numerals for chord roots with accidentals in a major key

Now what if I allow accidentals even in the root of the chord, still staying in the key of C major? For example:

Ebm (Eb Gb Bb)? Answer: bIIIm

F#dim7 (F# A C Eb)? Answer: #IVdim7

Bb (Bb d F)? Answer: bVII

C#m(maj7) (C# E G# B#)? Answer: #Imaj7

For the root, I use the same roman numeral and put a flat ("b") or sharp ("#") on the front to show how the root has been altered from the normal note in the scale. Then I add on the usual chord naming parts.

For example, Ebm. The normal note in C major would be E, roman numeral III. So Eb is bIII. Then add on the decorations "m" for minor: bIIIm.

For example, C#maj7. The normal note in C major would be C, roman numeral I. So C# is #I. Then add on the decorations "m(maj7)" for a minor major seventh chord: #Im(maj7).

Notice that when identifying notes with letter names, we stick "b" and "#" after the letter. But when identifying notes with roman numeral names, we stick "b" and "#" before the letter.

What do "b" and "#" really mean?

I chose my example from C major, but I swept a key fact under the rug: with roman numerals, "b" and "#" mean "lower a half-step" and "raise a half step".

To illustrate, suppose I'm in the key of D major. What is the roman numeral name for Fm (F, Ab, C)?

The root is F.

The normal "flavor" of F that appears in the key of D major is F#, a.k.a. IV.

So, in the key of Bb major, the chord E7 is called #IV7 in roman numerals.

Key point: The roman numerals might have "b" or "#" tacked on in front, depending on if the root of the chord is a half-step lower ("b") or higher ("#") than the normal note as it appears in the major scale. This happens even when the letter name does not have "b" or "#". For example, in D major, Fm, but bIIIm. In Bb major, E7 but #IV7.

Wait, what about the minor keys?

This post is quite long enough, so I'm going to put the minor keys in another post. Poor minor keys, always being deferred.

The C#dim7 comes from the key of D minor, and is making the following Dm chord seem more inevitable. It is VIIdim7 in the key of D minor, and can also be seen as a rootless A7b9, a.k.a. V7b9 in the key of D minor.

Just seeing your new note now, PS88 re: series leading up to dim7 chords, but have not gone through it yet.

We had tossed about D minor before for this section. I chose it originally I think because of the Bb, C#. But we are certainly not there long.

Since this section is largely construed from development of movement 1, would it be safe to say that we are passing through D minor, shortly visiting F major and then heading straight home to Bb Major?

Sorry, but unfortunately I mostly think in Black and White and have a very difficult time with Grey.